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The successful coexistence of cognitive radio systems with licensed system requires the secondary users the capability of interference-awareness, i.e., knowing which spectrum bands are occupied by primary users, i.e., the legacy users. Spectrum sensing thus is a key enabling module, which usually models the sensing process as a binary hypothesis testing assuming known signal distribution. However,...
Wireless propagation phenomena including multipath pose significant challenges to reliable spectrum sensing which is a fundamental requirement for dynamic spectrum access and system coexistence. In this paper, an optimal detection technique along with two reduced-complexity alternatives, modified energy detection (MED) and equal gain detection (EGD), are proposed to improve the detection probability...
Cognitive radios (CR) are regarded as a viable solution to enabling flexible use of the frequency spectrum in future generations of wireless systems by taking advantage of spectrum holes, that is idle frequency bands not actively used by primary users (PU) for licensed transmissions. The actual utilization of a spectrum hole is determined by its duration (implied by the time interval between two PU...
In this paper, we consider the problem of sensing a primary user in a cognitive radio network by employing multiple antennas at the secondary user. Among the many spectrum-sensing methods, the predicted eigenvalue threshold (PET) based method is a promising non-parametric blind method that can reliably detect the primary users without any prior information. Then, a simplified PET sensing method, which...
The performance in signal detection is evaluated by the error (false-alarm and missed-detection) probabilities. However, calculating these probabilities is a difficult task in practice. This paper studies the asymptotic behavior of the energy-detector and the estimator-correlator by means of the Stein's lemma. The Stein's lemma is an information-theory result that provides the best achievable error...
Wireless communications are prone to both unintentional and intentional RF interference. Such interference has significant impact on the reliability of packet transmissions. In this paper, we consider interference mitigation in frequency hopping (FH) systems. We employ cognitive radios (CRs) for proactive interference sensing in such systems. Through this proactive approach, we propose a scheme for...
To tackle the problem of performance degradation of traditional spectrum sensing technique with energy detection under the circumstances of weak signal and non-Gaussian environment in cognitive radio (CR), a novel spectrum sensing method based on suprathreshold stochastic resonance (SSR) is proposed in this paper. Through the resonance between the primary user (PU) signal and noise by introducing...
Compressive spectrum sensing techniques present many advantages over traditional spectrum sensing approaches, e.g., low sampling rate, and reduced energy consumption. However, when the spectral sparsity level is unknown, there are two significant challenges. They are: 1) how to choose an appropriate number of measurements, and 2) when to terminate the greedy recovery algorithm. In this paper, a compressive...
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